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Hello all:
After a lot to walk and to make infinite coils and circuits of all the books that he found, decided to rediscover the old circuit of the Sandbanks there now for the years 87 modified with the name of PROSCAN. At the beginning the only thing that notices of different was the printed circuit, the form of generation of the tension of 10 volts through the U6 555 and lastly the elimination of the Jfet channel P for only a transistor T4.
Once armed, the problems began. It could not achieve the tension in the entrance of the regulator U7, observing the PCB attentively found the error and I obtained the requested tension. The problems continued, the exit 6 of U3 appeared with interferences, to eliminate them I had to change the condenser C8 of value but it diminished the band width and it lost sensibility and I lost interest in achieving that for once it worked.
One week it takes meditating and observing other circuits like the microcontroller P.I. of Mark Stuart and I decided to modify the Proscan. First the IC LM318 places with all the components around the same one (it copies of that of Stuart) and the exit 6 of U3 was clean and perfect. Then I carried out the following modifications in function of the times and tensions that are the essence of the circuit.
1 - it modifies the work cycle to 50% of U6 so that they are loaded even the condensers and alter the frequency to 600 Hz., now the tension in the entrance of the regulator U7 arrives at 18V.
2 - it alters the width of the pulse from U1 to 80uS, changing the value of C3 this is achieved.
3 - I changed U8 for the CD4011 and the values of the condenser C21 and the resistances R32,R35 and R36 so that they give me the following values: pin 3 of U8: 28uS, pin 10 of U8: 40uS
4 - a condenser of 3,3 uF/25V was added among the exit of U5 and S1
5 - I work with a battery of 12V 1,2 Amp that gives me good autonomy and stability in the tensions.
Anyone can request me the changes that I made to the PCB, the Proscan modify with the since Corel Draw I don't dominate any autocad to make printed circuits.
It is everything, achieve an incredible sensibility and I feel very satisfied for the carried out work.
Carlos Daniel Fidel
[email protected]
Capacitors
C1 4700uF/16
C2,C13 47nF/63
C3,C11,C14 100nF
C4 1nF/63
C5,24,C15,C16,C17,C18,C18 100uF/25
C7,C10,C12 100nF
C8 5,6pF
C21,C22,C23 4.7nF
Diode
D1,D2,D3,D4,D6 1N4004
D7 BY407A
Trimers
P2 100K
P3 10K
P1 220K
Resistor (1/4W, 5%)
R1 39K
R2,R3,R10,R25 1K
R4,R8 330
R5;R19 220
R6,R15 100
R7 470
R11,R18 1M
R14,R16R23,R26 10K
R17,R21 2.2K
R20 6.8K
R22,R32,R35 12K
R33,R36 8.2K
R34 100K
R709 220K
Transistors
T1,T4 BC560C
T2 TIP41C
T3 BF245
IC´s
U1,U5,U6 555
U2 7905
U3 LM318
U4 741
U7 7810
U8 CD4011
Other
L1 Search coil, 20 cm diameter of 27 winding of insulated copper(0,5mm)
S1 Famale Jack Phones for PCB (optional)
Batery 12V. 1,2 Amp.
After a lot to walk and to make infinite coils and circuits of all the books that he found, decided to rediscover the old circuit of the Sandbanks there now for the years 87 modified with the name of PROSCAN. At the beginning the only thing that notices of different was the printed circuit, the form of generation of the tension of 10 volts through the U6 555 and lastly the elimination of the Jfet channel P for only a transistor T4.
Once armed, the problems began. It could not achieve the tension in the entrance of the regulator U7, observing the PCB attentively found the error and I obtained the requested tension. The problems continued, the exit 6 of U3 appeared with interferences, to eliminate them I had to change the condenser C8 of value but it diminished the band width and it lost sensibility and I lost interest in achieving that for once it worked.
One week it takes meditating and observing other circuits like the microcontroller P.I. of Mark Stuart and I decided to modify the Proscan. First the IC LM318 places with all the components around the same one (it copies of that of Stuart) and the exit 6 of U3 was clean and perfect. Then I carried out the following modifications in function of the times and tensions that are the essence of the circuit.
1 - it modifies the work cycle to 50% of U6 so that they are loaded even the condensers and alter the frequency to 600 Hz., now the tension in the entrance of the regulator U7 arrives at 18V.
2 - it alters the width of the pulse from U1 to 80uS, changing the value of C3 this is achieved.
3 - I changed U8 for the CD4011 and the values of the condenser C21 and the resistances R32,R35 and R36 so that they give me the following values: pin 3 of U8: 28uS, pin 10 of U8: 40uS
4 - a condenser of 3,3 uF/25V was added among the exit of U5 and S1
5 - I work with a battery of 12V 1,2 Amp that gives me good autonomy and stability in the tensions.
Anyone can request me the changes that I made to the PCB, the Proscan modify with the since Corel Draw I don't dominate any autocad to make printed circuits.
It is everything, achieve an incredible sensibility and I feel very satisfied for the carried out work.
Carlos Daniel Fidel
[email protected]
Capacitors
C1 4700uF/16
C2,C13 47nF/63
C3,C11,C14 100nF
C4 1nF/63
C5,24,C15,C16,C17,C18,C18 100uF/25
C7,C10,C12 100nF
C8 5,6pF
C21,C22,C23 4.7nF
Diode
D1,D2,D3,D4,D6 1N4004
D7 BY407A
Trimers
P2 100K
P3 10K
P1 220K
Resistor (1/4W, 5%)
R1 39K
R2,R3,R10,R25 1K
R4,R8 330
R5;R19 220
R6,R15 100
R7 470
R11,R18 1M
R14,R16R23,R26 10K
R17,R21 2.2K
R20 6.8K
R22,R32,R35 12K
R33,R36 8.2K
R34 100K
R709 220K
Transistors
T1,T4 BC560C
T2 TIP41C
T3 BF245
IC´s
U1,U5,U6 555
U2 7905
U3 LM318
U4 741
U7 7810
U8 CD4011
Other
L1 Search coil, 20 cm diameter of 27 winding of insulated copper(0,5mm)
S1 Famale Jack Phones for PCB (optional)
Batery 12V. 1,2 Amp.
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